As an insulating resin composition for covering an electric wire for automobiles, there is known, for example, a resin composition for an electric wire insulator wherein from 60 parts by mass to 90 parts by mass of a metal hydroxide has been blended to 100 parts by mass of a base resin composed of from 55 parts by mass to 98 parts by mass of a polyolefin-based polymer and the remainder of a polyamide and the polyamide is a copolymer of polyamide 6 with polyamide 66 (see, for example, Patent Literature 1). However, this resin composition has proved to have a problem that the added amount of magnesium hydroxide is so large that the resin composition cannot satisfy the battery fluid resistance according to ISO 6722 (2006 version).
Then, in order to satisfy the battery fluid resistance, studies for satisfying flame retardancy and battery fluid resistance without using magnesium hydroxide as much as possible were carried out, so that addition of a halogen-containing flame retardant was discovered (see, for example, Patent Literature 2). As a result, a blend system by which both battery fluid resistance and flame retardancy are satisfied simultaneously was discovered, but this caused an adverse influence, that is, a problem that low-temperature resistance and wearness deteriorate.
Besides, resin compositions provided with flame retardancy have been known (see, for example, Patent Literatures 3 to 6), but none of them can satisfy flame retardancy, battery fluid resistance, low-temperature impact property, and wear resistance simultaneously.